The House of Representatives filed a lawsuit in D.C. District Court to to block President Trump from moving federal funds to a border wall project in Texas.

The suit names Treasury Secretary Steven Mnuchin as the lead plaintiff, as well as acting Secretary of Defense Patrick Shanahan and Homeland Security Secretary Kirstjen Nielsen. It was announced as Trump visited Calexico, Calif., to see a segment of newly constructed wall and to hold a border security roundtable.

“This case arises out of the unconstitutional actions taken by President Donald J. Trump’s Administration to construct a wall along the southern border of the United States,” the lawsuit states.

Speaker Nancy Pelosi, D-Calif., announced Thursday a special House committee made up of Democratic and GOP leadership voted to file the lawsuit, but the panel is dominated by Democrats who hold the majority in the chamber.

Pelosi had threatened court action to block Trump, who used a national emergency declaration to justify diverting $3.6 billion in unspent military construction funding to the wall project.

Congress passed a measure to revoke the national emergency with the help of a small group of Republicans, but Trump vetoed it.

Sixteen states have already sued Trump to block the wall funding grab.

In the lawsuit, Democrats accuse the president of breaking the law by spending money already designated by Congress.

“The Administration’s actions here demonstrate a shocking disregard for the Appropriations Clause, which protects Congress’s ‘exclusive power over the federal purse,’ and is both ‘a bulwark of the Constitution’s separation of powers among the three branches of the National Government,’ and ‘particularly important as a restraint on Executive Branch officers,’” the lawsuit states.

Democrats have argued the president’s emergency declaration is unwarranted because there is no crisis at the border. Border crossings by families have dramatically surged in recent months, border patrol officials said, exceeding their capacity to hold migrants.

Border patrol officials said 76,000 migrants crossed illegally into the United States in February.